Where do I start with CAD?

Hello, I would like to make some things out of plastic. I've done a lot of 3D modelling work, mainly for animation, which I know is insufficient when it comes to making actual stuff. I'm guessing that making a model into real live plastic isn't going to be as easy as just saving a DXF and sending it somewhere to be, er "made real" (I don't even know the term for that).

So what I want to know is- what books should I get? I figure start there rather than ask a bunch of annoying questions. I think I can handle the software, it's the reality stuff that I don't know. I'm probably going to need to learn about different types of plastics. And how much do I need to know about the equipment that actually does the "realization"? Can you tell I don't know what I'm talking about?

The stuff I want to make is pretty simple- sort of like a frisbee to start.

thanks very much

Reply to
mrbog
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It is actually as simple as sending the 3D cad data to a manufacturer. Save the 3D file as IGES or STL, and send it to a stereolithography manufacturer. Most of them can manufacture from this data in resin or various plastic materials, and you should get your first-off part in less than a week.

If you're happy with the product and your volumes are high, then you can use the same model to get tooling made.

You will need dimensioned drawings only for quality control and inspection.

Dave

Reply to
dakeb

That bit of advise is loaded with issues. For one a sterolith part can be made with all types of manufacturing issues. Specifically speaking undercuts. Undercuts are areas in a part with will cause it NOT to release from a cavity/injection mold. If you're really looking to start with a frisbee like part take a look in a kitchen and look for a baking tin/mold. The side walls are drafted ( tapered ) to make it easy for the cake/part to release from the mold. Tapering walls on injection molds are essential for manufacturing. I would recommend that you do a google search on the web for plastic part design. I'm sure there is a ton of materials to bring you up to speed to make easy parts. One other thing, a part can be drafted many ways. Leaving draft up to the toolmaker can result in a part that is non-functional. The best way to get a part produced to your expectations is to draft all the surfaces. That way there is no surprises or costly charges to modify the injection mold to your original design intent.

Good Luck

manufacturer.

inspection.

Reply to
GS

One other bit of advice. It sounds like you're wanting to do something like this on your own. I hope you realize the costs involved. A prototype part can cost thosands of dollars and really won't work that well. They're usually more brittle than real molded parts. They're just to test looks and basically functionality, not to be used by your potential customers.

If you're looking to injection mold something, you'll need tens of thousands of dollars to have a tool built. When you're into that kind of dollar range, and since you have no plastics knowledge, you'd be much better off hiring an engineering consultant to do this work for you. Sure it might cost thousands of dollars for their expertise, but you'll make sure the 50,000 tool you'll be building won't end up as scrap metal.

Cj

GS wrote:

Reply to
Chris Fawcett

Awesome, thanks very much. Can you recommend a stereolithography place? Also I probably still need to learn about plastics- do I ask the stereolith place to give me samples or should I get a book or something?

thanks very much

Reply to
mrbog

Depends on your locality. Do a google search for stereolithography or 'rapid prototyping'.

See the link for basic principles.

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Speak to your local rapid prototyping shop, and they will explain the process and probably recommend vacuum casting for lowish number batch production. They will recommend plastics to you based on your application. The plastics field is complex, and you will not learn it in a few days, rather leave it up to the experts.

Dave

Reply to
dakeb

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TRY THIS

Reply to
Jessica

For prototype parts try Design Prototyping Technologies (DPT) they are out of New York. I use them on a weekly basis and I am down in Mississippi so they don't have to be local. They also have online instant quoting. Parts like a Frisbee are going to be expensive. It a simple part but there is a lot of plastic to it. DPT has a 3 day turn around. Works great.

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As far a adding draft to your part, Since it sounds like you have little experience with plastic part design. What you can do is meet with a Tool Shop let them quote a tool. After you have found a tool price you can live with, the next step usually would be a tool concept review. At this review the tool shop will recommend where and how much draft is needed, but don't let them walk all over you. They are out to make the tool as simple as possible and I know that is what I use to do to people. When you leave the review you can go work on your part adding the draft that was recommended or you could let the tool shop modify your part for you if you can afford their CAD time. Just make sure that you review every surface on the part before any steel is cut. Another way that you can go is prototype tooling. Depending on what kind of volume you are planning on, you can make what some companies refer to a prototype tool. They are good for 100's and in some cases 1000's of parts before the tool is shot. The price on these tools are

1/4 that of a production tool, but press time when you are actually running the tool in most cases will be higher. There are some shops out there that specialize in prototype tooling.

As far as the type of plastic to use. That is a tough one. I don't think that you will be able to find a book that has enough information in it to help you chose the plastic to use like Plastics for Dummies. You might be better off talking about it with your tool shop. They should be able to help you or at least point you in the right direction.

When it comes to drawings, The tool shop will probably require one for quoting purposes. Nothing with a lot of dimensions, just the basic size. Just make sure to add the note that dimensions are controlled by latest 3D data.

Good Luck John

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Reply to
John Morrison

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